Dmitry Grinberg showcasing a charlieplexed Led matrix with a single PIC16F688 microcontroller.
"This project is pretty cool for a few reasons, and driving a huge LED matrix with a single 8-bit controller is just one of them. The idea was born when I bought 120 LEDs of the wrong type, and decided to do something with them.
With that many LEDs, there are only a few things you can do, and a matrix is the natural first-place-winner in the competition of those ideas. One of the LEDs did not work, so a 12x10 matrix was out, so I settled for an 11x10 matrix. This meant I had to drive 110 LEDs. The only controller I had free was a PIC16F688 with 11 pins that can be used for output. After deciding not to use any other chips, charlieplexing was the way to go. The maximum number of LEDs one can charlieplex using N pins is N * (N - 1), so for 11 pins that number is 110. What a coincidence! :)"